The present invention is directed to a method and apparatus for providing access to a data network. More particularly, the present invention is directed to a method and apparatus by which elements in a first communication network that have no direct access to a data network can be provided with such access via overhead channels employed in the first communication network.
It is known in the communication network environment to provide remote management elements which can monitor and control aspects of the communication network. One example of such a communications network arrangement is an optical fiber network referred to as the Synchronous Optical Network (SONET). In this network an operation support system can remotely monitor network element equipment. As an example, in SONET an optical line system end terminal or repeater equipment, such as that provided by Lucent Technologies, and large capacity terminal equipment, also available from Lucent, both have a port available to provide alarm and status information to an operation support system. This port is referred to as the X.25 Telemetry Port. An example of an operation support system is the Element Management Controller-2000 (EMC-2000) developed by ATandT/NCS (Network and Computing Service Division).
FIG. 1 provides a block diagram representation of an arrangement employing such a remote monitor and controller with communication network elements. In FIG. 1 the communications network includes such elements as communication stations 101 and 102. Of course, the communications network would in all likelihood consist of multiple stations beyond those shown in FIG. 1. A station could be a central office (CO) in a communication network. Each station would include terminal equipment (e.g., 1031 and 1032) referred to in a specific example as an optical line system end terminal. The stations are linked together via optical fiber links 104. To compensate for the distance limitations which arise in terms of transmitting information over the optical fibers, repeater elements 105 may also be employed in the network interconnecting the communication stations 101 and 102. Each of the communication stations may also include a network interface device 1071 and 1072. Such an interface device provides direct connection to a data network 110. The data network provides access from the communication network to a remote monitor and controller device 115. As each communication station may include multiple optical line system end terminals and multiple large capacity terminals, data switches 1061 and 1062 are included to concentrate the multiple X.25 Telemetry Ports on the various pieces of equipment to provide a single connection to the network interface.
In one example deployment each large capacity terminal and optical line system end terminal included in a communication station such as 101 has a port for communicating alarm and status information. In the example this is the X.25 Telemetry Port and that port is connected to a switch (in the example an X.25 switch) co-located in the station or central office. The X.25 Telemetry Ports are then connected to the network interface via the switch. The network interface provides connectivity to a network such as ATandT""s Dedicated Wide Area Network (DWAN). The operation support system, that is the remote monitor and controller 115, is located at a centralized operation center and can access the X.25 Telemetry Ports over the data network.
Data network connectivity to the X.25 switch at each central office or station is provided internally by ATandT or leased from a local exchange carrier depending on circuit availability and bandwidth needs.
In one proposed architecture, the EMC-2000 receives most of its data through a SONET node that is designated as a gateway network element. For example, on a typical SONET ring two nodes would be gateway network elements, one the primary element, the other an alternate to provide redundancy. All optical line systems that are part of this ring utilize the SONET data communication channel to communicate alarm and status information to the EMC-2000 via the gateway network element. These gateway network elements are always located in offices that have network access. In order for the controller 115 to obtain optical line system performance monitoring data, however, it must have access to the data port, the X.25 Telemetry Port, on each optical line system end terminal.
The inventors have determined that as deployment progresses the topologies of some of the SONET rings have forced some of the optical line system end terminals to be physically located in offices that do not have network access. For example, certain offices or stations may be remotely located or placed in isolated areas. These isolated areas typically are not provided with direct access to the data network. Nonetheless, these offices require access, via a port, to the data network so as to supply to the controller information on behalf of the optical line system elements and the large capacity terminals associated with that end terminal. Known system configurations do not provide any paths for such isolated office operations.
The present invention provides a new system arrangement and method by which a remotely located or isolated office related to an end terminal needing data network access is provided with access via a network interface associated with another optical line system end terminal. In particular, in accordance with an embodiment of the present invention, the system employs overhead channels available on the communication network to provide an alternate path from the isolated optical line system to an optical line system end terminal that has direct access to the data network. Hence the isolated optical line system can exchange information with a remote monitor and controller.
In a further embodiment of the present invention a network is arranged so as to provide multiple subnetworks. Overhead channels which are available in the communication network can be employed so as to provide a redundant reporting path relating to the subnetworks. More particularly, given a first subnetwork and a second subnetwork which both have a physical appearance in the same station or central office, the second subnetwork can be utilized as an accessing vehicle for obtaining alarm and status information regarding the first subnetwork over overhead channels available on the second subnetwork. Alternatively, the first subnetwork can operate as a redundant or back-up path for providing status and alarm information relating to the second subnetwork utilizing overhead communication channels available on the first subnetwork.
In a more specific embodiment the arrangement uses one or more order wire channels available in the overhead channels.
Further advantages of the present invention will be described below in connection with the detailed description of the invention.